The St. Marys River is the connection between two Great Lakes Lake Superior and Lake Huron. This site covers parts of the lower portion of the river from Echo Bay at the north end of Lake George to Maxton Bay near where the waters widen into Lake Huron. The river varies in width, sometimes narrow, but often widening into large bays and lakes. Along the shoreline are numerous and diverse marshes, wet shrublands and swamps. This IBA complex includes bays, wetlands and adjacent waters of several parts of the St. Marys River and thus it includes: Echo Bay, Pumpkin Point, and Hay Marsh on the Ontario side, and southern Lake George, northern Munuscong Lake, Raber Bay and Maxton Bay in Michigan. The size of the area given here is a rough estimate that covers Lake George, Munuscong Bay and the various disjunct marshes and bays of interest in this IBA, but does not include all the connecting waters. Mink, River Otter ,Muskrat, and Beaver are all found here.
Numerous Black Tern colonies are found in the wetlands of the St. Marys River. Probably over 300 Black Terns nest here (combining data from different years in the 1990s). Because there are no estimates for the Canadian population of Black Terns, the national IBA threshold was set at 50 pairs. The colonies on the Canadian side of the St. Marys River clearly exceed this number. The largest known colony on either side of the border is the one at Hay Marsh on St. Joseph Island, which had an estimated 100 pairs in 1996. Other breeding species of interest include the nationally vulnerable Least Bittern (Echo Bay), Common Tern (160 nests) and Bald Eagle (Hay Marsh). Many pairs of Osprey forage in Echo Bay and the wetlands at Pumpkin Point.
During migration, waterfowl congregations are notable. At least 23 species of waterfowl occur on the east side of Lake George scoters, diving ducks, puddle ducks, mergansers and geese are all represented. Lesser Scaup are one of the most abundant species here, with up to 6,000 having been recorded in the fall. Also of interest were 12 King Eiders that were recorded in October, 1995 in Munuscong Bay.
Two other species are worthy of note even though they do not actually use this site. In the spring, thousands of Common Loons pass over the area heading in a northwesterly direction (towards Lake Superior). In the fall probably well over 10,000 Red-necked Grebes fly by in the opposite direction, presumably heading from Lake Superior to northern Lake Huron. These birds do not appear to come down onto the St. Marys River in any numbers.
BirdLife International (2021) Important Bird Areas factsheet: St. Mary's River Complex (Echo Bay ON to Maxton Bay MI). Downloaded from http://www.birdlife.org on 19/10/2021.